Police seize weapons including chemical spray, knives, shields and a stun gun

Six people were injured and at least 13 were arrested after far-right protesters and opposing demonstrators clashed on Saturday in the largest city of Oregon in the western United States.

There were approximately 1,200 demonstrators in downtown Portland at the peak of the protests. The city called in its entire force of 1,000 police officers in response to what the Portland Police Bureau called "civil disturbance", which has attracted national attention.

Video footage posted on social media shows that protesters with red "Make America Great Again" caps and counterprotesters in black fighting with each other, and police in riot gear trying to keep the two sides of demonstrators from separate.

Over the course of the daylong demonstration, police seized weapons including chemical spray, metal and wooden poles, knives, shields and a stun gun, Portland Police Chief Danielle Outlaw told reporters on Saturday evening.

The protests clogged the streets of Portland and disrupted public transit. The arrested individuals face a range of charges, including disorderly conduct, interfering with police, resisting arrest and unlawful use of a weapon, said Outlaw.

The rally was organized by the Proud Boys, a US-based all-male far-right group, founded in 2016, which promotes white nationalism, gun rights and "Western Chauvinism" on its website. The Southern Poverty Law Center, which advocates against bigotry, has designated the Proud Boys as a hate group.

The Proud Boys said the goal of the rally was to oppose anti-fascist demonstrators, collectively called "Antifa" and known for wearing masks and all-black clothing. They want Antifa to be declared a domestic terrorist organization.

New battleground

Before the demonstration started, US President Donald Trump tweeted that "Major consideration is being given to naming ANTIFA an 'ORGANIZATION OF TERROR.' Portland is being watched very closely. Hopefully the Mayor will be able to properly do his job!"

In response to Trump's tweet, Portland Mayor Ted Wheeler told CNN that the president was not "helpful" in addressing a "potentially dangerous and volatile situation". "Adding to that noise doesn't do anything to support or help the efforts that are going on here in Portland," he said.

Portland has become a new battleground for far-right and far-left extremists. Almost two months ago, clashes between another far-right group, Patriot Prayer, and counterprotesters led to four arrests and four injuries, according to Portland Police Bureau.

In 2017, thousands of people skirmished in fights between pro-Trump groups and counterprotesters at a rally in Portland, following a stabbing on public transit train after a man reportedly harassed a woman wearing a hijab.

The debate on white supremacy has recently been fueled in the US after a shooter killed 22 people in El Paso, Texas, early this month. Before going on the killing spree, the suspect posted a manifesto online, which is filled with white supremacist language and racist hatred aimed at immigrants.

Clint Watts, a senior fellow at the Foreign Policy Research Institute and a former FBI counterterrorism expert, has said that the country doesn't take white nationalism seriously enough and suggested legislation to designate white supremacy as domestic terrorism.

On the other hand, Republican Senators Ted Cruz and Bill Cassidy have introduced a congressional resolution calling for anti-fascists to be declared domestic terrorists.

But experts said it's difficult to determine whether Antifa is a terrorist group. "Antifa is not a highly organized entity and has not persisted over time," said Gary LaFree, chair of the Department of Criminology and Criminal Justice at the University of Maryland, in an article for the NBC News website on Saturday.

"Terrorism is a method, not a group or an individual" and "measuring the motives of individuals is complicated", he said.