SINGAPORE — President Trump made last-minute preparations Monday for his meeting with Kim Jong Un in the shadow of his blow-up with western allies at the G-7 summit — a good sign to his backers, not so good to others.

“Great to be in Singapore, excitement in the air!” Trump tweeted during a low-key day ahead of his historic summit with the nuclear-armed dictator of North Korea.

While Trump aides said his battles with Group of 7 economic allies over trade policy show that he will fight for what he wants, others said his inability to deal with global friends bodes ill for his chances with nuclear-armed adversary Kim.

Hailing Trump’s pushback to criticism from Canadian Prime Minister Justin Trudeau, White House senior economic adviser Larry Kudlow told CNN’s State of the Union that the president “is not going to let a Canadian prime minister push him around … Kim must not see American weakness.”

Trump “is not going to permit any show of weakness on the trip to negotiate with North Korea, nor should he,” Kudlow said.

Foreign policy analysts said the G-7 discord — Trump refused to endorse a group communique, saying other members use unfair trade practices against the United States — calls into question his ability to strike a good deal with anybody. While the United States and Canada fight over dairy trade, the Kim meeting concerns the fate of nuclear weapons.

“If Trump can’t negotiate a deal on milk with one of our closest allies, how is he going to get a deal on nuclear disarmament with one of our greatest foes?” tweeted Michael McFaul, ambassador to Russia during the Barack Obama presidency.

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Trump’s meeting with Kim, the first ever between a sitting U.S. president and a North Korean leader, is scheduled for 9 a.m. Tuesday, local time — 9 p.m. Monday in Washington, D.C.

A day after landing in Singapore, the former British…