South Korean President Lee Jae-myung speaks during a press conference in Seoul on June 4.

US President Donald Trump is set to host South Korean President Lee Jae Myung in their first summit today.

Despite being one of the United States’ key strategic and economic partners in Asia, the decades-old alliance is being put to the test as Trump reshapes US diplomacy.

Here’s what could be on the agenda for today’s meeting:

US troops in South Korea: Trump is expected to pressure Lee to commit to spending more on defense.

Ever since he was on the campaign trail, Trump has talked about the dollar amount that South Korea pays for the presence of US troops in South Korea, of which there are about 28,500 personnel.

In October, the US and South Korea reached a five-year cost-sharing agreement for American forces based in South Korea ahead of Trump’s election victory in November.

Trump said South Korea pays just over $1 billion but should be paying up to $10 billion for that security guarantee. That was not addressed during the trade agreement reached by both nations a couple of weeks ago. So we’re acutely attentive to whether or not that’s going to come up today.

The US is also expected to demand that it embrace flexibility for US troops based in South Korea, which Lee said “cannot be easily agreed on,” on his way to Washington. But Lee left room for further discussions on the issue, saying “future strategization” of the role of the US troops in Korea was needed.

“I think it’s interesting whether or not the function of these troops comes into the conversation, the potential shift of these troops… going from a counter for North Korea’s purposes to maybe shifting some of the troops’ focus to being a counter towards China,” Seoul correspondent Mike Valerio told CNN’s Rosemary Church on air.

North Korea: Lee and Trump are likely to find common ground in trying to bring North Korean leader Kim Jong Un back to the negotiating table to talk about its ever-expanding nuclear program, Valerio said.

Their meeting comes just days after North Korea claimed to have test-launched two new air defense missiles. South Korea’s summit with neighboring Japan on Saturday also stoked criticism from Pyongyang. North Korea dismissed the meeting, in which denuclearizing the Korean peninsula was discussed, as an attempt to curry favor with the US.

Shipbuilding: South Korea is among the top countries leading the global shipbuilding industry.

“The political class here in Seoul, and certainly the presidential office here in Seoul, is saying that they want to help make American shipbuilding great again,” Valerio said. “So we’re looking for any sort of investment signal in this meeting.”

The two countries announced cooperation in shipbuilding in trade negotiations last month. Lee and Trump are expected to discuss the details.