The arrival of three Chinese warships in Sydney harbour was not a surprise, Scott Morrison has said, despite the fact that the government did not announce the visit in advance.

On Monday an army frigate, an auxiliary replenishment ship and an amphibious vessel from the People’s Liberation Army were docking at Garden Island for a four-day stopover.

It comes on the eve of the 30th anniversary of the Tiananmen Square massacre, and only a week after reports of Chinese military tailing Australian navy vessels transiting through the South China Sea.

Speaking in the Solomon Islands, the prime minister said the government had “known about that for some time”.

“This was an arrangement, a reciprocal visit because Australian naval vessels have visited China,” he said. “They were returning after a counter drug-trafficking operation in the Middle East.

“That is a further demonstration of the relationship that we have and this had been in train for some time. It may have been a surprise to others but it certainly wasn’t a surprise to the government.”

Asked whether the arrival of the ships was appropriate given the anniversary of the massacre, Morrison said: “No, I think any reading into timing could be subject to a bit of over-analysis.”

In the lead up to the anniversary, a Chinese government minister defended the bloody crackdown on student protesters, with the defence minister, General Wei Fenghe, telling a regional security forum in Singapore on Sunday it was the “correct” policy.

Morrison said the country’s rare acknowledgement of the event was “not a new position”, but said Australia would “express its views through the foreign minister on that matter” in the coming days.

Sailors on board one of the three Chinese ships that arrived in Sydney Harbour on Monday. Photograph: Peter Rae/AAP

Morrison’s visit to the Solomon Islands is the first by an Australian prime minister since 2008. On Monday he announced a $250m grants program for the country and an easier path for islanders to get work in Australia as part of Australia’s attempts to counter China’s increasing role in the Pacific.

China is now the largest trading partner of the Solomon Islands, and is actively courting the country’s leaders to abandon ties with Taiwan and join Beijing’s Belt and Road Initiative.

The country’s prime minister, Manasseh Sogavare, has said he is reviewing the relationship with Taiwan.

On Monday, Morrison refused to weigh in, saying it was a decision for the Solomon Islands.

“Our relationship, our family relationship with the Solomon Islands is to support them in the decisions that they take as an independent sovereign government and so they will work through their process on that issue,” he said.

The US has accused China of undermining stability on issues ranging from the South China Sea to Taiwan. On Monday Morrison warned against viewing China and US relations through a “binary prism”.

“I think we have to be careful not to see what are ongoing and upgrading relationships here for Australia and the Pacific through those binary terms of the United States and China,” he said.

“They have their interests in the region, as do others. Our relationship with the Solomon Islands, our relationship with the Pacific transcends all of that.

“There is a great risk and a great danger in an analysis that only can see the world through those – through such a binary prism.

“I certainly don’t. Australia certainly doesn’t. Australia welcomes the economic growth and advancement of China with their economy.”