El Salvador's strongman president, Nayib Bukele , is sending thousands of troops to Haiti to boost the island's push to wipe out its gang problem — and find four of his military personnel who were captured in a recent ambush.

Bukele called President Trump on Tuesday to make sure he had no problem with this major military escalation, to which Haiti's government has agreed.

"Do what you have to do," Trump told him, according to sources briefed on the call.

Why it matters: If it works, Bukele's troop surge could stabilize Haiti, a country 700 miles from Florida that has been devastated by deadly gang violence and has lacked a president since the last one, Jovenel Moise, was assassinated five years ago.

If it doesn't work, it could increase Haiti's death toll well beyond the 5,700-plus killed in gang violence this year, embarrass Bukele and mark yet another failed international effort to restore stability to the country.

Haiti also may be a test case for Bukele and security contractor Erik Prince — a Trump…