When Malaysian Prime Minister Najib Razak met U.S. President Donald Trump at the White House last month, they tried to forge more common ground on key issues and manage some of their differences. Although Najib and Trump made some progress as they commemorated the 60th anniversary of bilateral ties between Malaysia and the U.S., bigger tests will come in their bid to surmount deeper obstacles that stand in the way of really broadening the relationship.

Throughout the past 60 years, the United States and Malaysia have had to find ways to cooperate despite often stark disagreements on matters such as human rights, economic policy and U.S. foreign policy in the Middle East. During Barack Obama’s presidency, U.S.-Malaysia ties hit a new high, with both sides elevating the relationship to the level of a comprehensive partnership and Malaysia becoming a member of key U.S.-led initiatives, from the Trans-Pacific Partnership, or TPP, to the international coalition against the self-proclaimed Islamic State.

Yet despite those trends, recent years have also proven how difficult it is to forge closer ties. Even during the final years of the Obama administration, Najib’s crackdown on domestic dissent and ongoing investigations by the U.S. Justice Department into the high-profile corruption scandal involving Malaysia’s sovereign wealth fund, 1MDB—in which Najib is directly implicated—had complicated U.S.-Malaysia relations and imposed limits on what both sides could accomplish. When Trump came into office in January, his tough line on issues ranging from trade to immigration to North Korea initially set off alarm bells in Malaysia not just about bilateral ties, but also the U.S. role in Asia more generally.

Seen from this perspective, Najib’s visit to Washington was an opportunity for both sides to clear the air and attempt to make some progress in the face of recent difficulties. In his meeting with Trump and others in Washington, Najib sought to present Malaysia as not just a country expecting more from the U.S., but as a successful nation in its own right willing to contribute to a range of issues important to U.S. interests, including counterterrorism, North Korea, the South China Sea and the plight of the Rohingya in Myanmar. That dovetailed with Trump’s nascent foreign policy, in particular his stated desire to engage more closely with American allies and partners who were willing to do more not just for their own interests, but also for America’s own security and prosperity.

Trump and Najib made some tangible progress, agreeing to address prickly trade and investment issues, to further boost defense cooperation in existing areas like maritime security, counterterrorism and cybersecurity, and to continue dialogue on unfinished items such as Malaysia’s inclusion in a U.S. visa waiver program, which would enable Malaysians to travel to the U.S. without a visa for 90 days for tourism and business.

Challenges related to human rights and democracy are not new to U.S.-Malaysia relations, but they loom larger under Najib and Trump.

These steps were notable, given the initially gloomy outlook for ties at the beginning of the Trump era. Still, both sides will have to overcome several persistent challenges if they are to truly elevate ties any further. The first relates to the general issue of commitment. From Malaysia’s perspective, there are deep anxieties about how Trump’s transactional, protectionist and nativist “America First” vision will eventually play out and what that means for bilateral ties. In Washington, meanwhile, some are concerned about whether Najib’s diminishing domestic position may be leading him to align even closer with China, not just economically but on the security side too. Though this alarm is often exaggerated, it did not help that just hours before Najib met Trump, news broke about the second-ever visit to Malaysia by a Chinese submarine earlier that week.

The second challenge has to do with threat perceptions. Both leaders were keen to emphasize general solidarity on security issues, with Trump praising Najib for not doing business anymore with North Korea, and Najib assuring Trump that the Islamic State was a shared enemy. Their joint statement also contained particularly strong language referring to Chinese coercion in the South China Sea. Yet this rhetoric conceals the reality of disagreements that both sides must be conscious of and manage. These disagreements concern the wisdom of further isolating Pyongyang diplomatically, the balance between maximizing the opportunities and contending with the challenges posed by China’s rise, and avoiding an overly militaristic approach to fighting terrorism that can alienate parts of the Muslim world.

The third and final challenge relates to rights and democracy. Though this problem is not new to U.S.-Malaysia relations, it looms larger under Najib and Trump. Both leaders face unusually fierce criticism about their own personal records. Indeed, much of the commentary on Najib’s visit focused not on the substance of bilateral ties, but on the 1MDB scandal and Trump’s embrace of authoritarian leaders. Though both leaders might be tempted to ignore or downplay such criticism, leaving it to fester would be a mistake. This is a challenge that is here to stay and could even worsen given the political polarization in both countries, which could be exacerbated by next year’s midterm elections in the U.S. and general elections in Malaysia.

In their joint statement after their meeting, Najib and Trump committed to strengthening the comprehensive partnership between the U.S. and Malaysia not just for the sake of bilateral ties, but “to promote peace, stability, prosperity, and international consensus in the Asia-Pacific region and around the world.” That is an ambitious goal, and one that will be difficult to achieve if they don’t confront the tougher challenges head-on in the coming years.