Arsenal finished five points behind Manchester City in the Premier League last seasonArsenal boss Mikel Arteta accepts his side must strengthen in the transfer market if they are to become Premier League champions next season.
Arteta's side were beaten to the 2022-23 title by Manchester City.
The Gunners have been linked with a move for West Ham midfielder Declan Rice and are also closing in on forward Kai Havertz from Chelsea.
"Next season is going to be the toughest league in Premier League history," said Arteta.
"Why? It already was last year. I've been here [England] for 22 years and I've never seen a competitive level like that. So much quality, so much organisation, so many resources, so many good coaches.
"That's the level and to win the Premier League you have to be the best. That's why you have to strengthen."
Arsenal topped the table for much of the campaign but their challenge fell away after they suffered injuries to key players like William Saliba.
Although the Gunners finished second and secured a return to the Champions League, Arteta says it still "hurts".
"To this day, it still hurts me deep inside not to have won the Premier League after 10 months of fighting with City," he added.
"There were three or four injuries to important players and from then on, everything got complicated. When we had the full team, we were consistent. As soon as problems came, it wasn't enough for us.
"Our opponent was the best team in the world, the best squad in the world, the best coach in the world.
"We had no choice but to accept it and shake hands with the champion."
