How to have Ukraine's Volodymyr Zelensky at NATO's Hague summit and avoid a bust-up with US President Donald Trump? What to say on Kyiv's desire to join their alliance?
With NATO appearing on track to seal a deal on ramping up defence spending, another thorny issue now threatens to overshadow the gathering in three weeks: what to do about Ukraine?
When they met in Washington a year ago, NATO's leaders feted Zelensky, pledged more military hardware and vowed Kyiv was on an "irreversible path" for membership in their alliance.
That was before Trump's return to the White House ripped up Washington's support for Ukraine and upended the West's approach to Russia's three-year war.
Since he regained the US presidency, Trump had a dramatic Oval Office falling out with Zelensky, opened the door